1. Field of the Invention
The present invention relates to a gas turbine combustor using liquid fuel as its fuel and more particularly to a gas turbine combustor for an aircraft engine.
2. Description of the Related Art
FIG. 11 shows a prior art gas turbine combustor. In the figure, the gas turbine combustor 1 comprises a cylindrical casing 3 composed of an outer casing 3' and an inner casing 3" centered on a center line of rotation 50 of a turbine rotor blade 6. A cylindrical liner 2 is composed of an outer liner 2' and an inner liner 2" and is disposed within the casing 3 concentrically therewith.
Formed through the outer liner 2' and the inner liner 2" are an air hole 40 for supplying combustion air to a combustion chamber to form a flame holding area and a slot 41 for supplying dilution air to the combustion chamber to lower the temperature of combustion gas to a predetermined turbine inlet temperature and to reduce NOx.
Air supplied from a compressor to a space between the casing 3 and the liner 2 flows toward the turbine along the liner 2 and cools the outer surface of the liner 2. During the flow of air, a part of the air flows into the combustion chamber from the air hole 40 described above and the other part thereof flows into the combustion chamber from the slot 41 and cools the inner surface of the liner 2.
It is noted that a guide vane 20 at an outlet of the compressor is provided at the upstream side of the casing 3. A turbine nozzle 30 is provided at the downstream end of the casing 3. A fuel supply inlet 12, a fuel-air pre-mixer 13 and an igniter 71 are provided as shown in the figure.
Because the air cooling the liner 2 flows into the combustion chamber partially from the air hole 40 and the slot 41 as described above, there have been problems in that the liner 2 is not cooled equally, and a hot spot is apt to be created at an area downstream of the air hole 40. This causes a melt-down in which a part of the liner is melted and lost.
The hot spot is caused, partially, because the balanced temperature of the liner 2 can only becomes high, because the liner 2 is cooled by air having poor heat transfer characteristics, and because, due to the poor heat transfer characteristics, it can only use a liner material such as hastelloy X whose thermal conductivity is poor, though its high temperature strength is good.
Accordingly, it is a primary object of the present invention to provide a gas turbine combustor which prevents such a hot spot, which leads to a melt-down, from being produced, by use of a material having good thermal conductivity, though the high temperature strength thereof is small, as a liner material by cooling the liner 2 equally with liquid fuel having a heat transfer characteristic higher than that of air.